Nonmem model

From: Batul Parta - batulparta@yahoo.com Subject: [NMusers] Nonmem model Date: 12/17/2003 11:51 AM Dear all, I am having problems getting NM to estimate any parameters in the following situation. I have data on bactericidal effects of an antibiotic. The PK is fixed (one comp.). PD consists of three compartments: sensitive (comp. 2), non-sensitive (comp. 3), and non- replicating (comp. 4). PD data are log-transformed in the data file. My observations are the sum of comps 2 and 4. The nonmem codes are given at the end of this mail. My problem is that NM does not estimate anything but the two THETAs associated with the error terms. It converges all right but nothing else is changed from the initial estimates. In my data file, I have the usual stuff (date, time, amount) plus a CMT, which is 1 for the dose and 2 for the first (and only first) PD observation. Beside the model given below, I have tried one with no log-transformed data as well as one with a hypothetical compartment which is the sum of compartments 2 and 4. All have the same problem. Starting with different initial values doe not help either. Any suggestions? Best regards and thank you for your help, B. Parta